In the presence of O6-Benzylguanine (06-BG) tumor cell lines have demonstrated an increased sensitivity to alkylating agents such as nitrosoureas and procarbazine. The mechanism proposed for this property of O6-BG is in part attributed to its ability to inactivate an important enzyme involved in DNA replication and repair pathways called alkylguanine-DNA alkyltransferase (AGT). The objectives of the study are the following: (1) To define a dose of O6-BG that depletes all AGT activity in >90% of the AA or GM cases evaluated. (2) To evaluate the associated toxicities both quantitatively and qualitatively. GCRC expertise would be used to administer the pre-surgical O6-BG administration and subsequently to provide consistent data with daily blood draws and toxicity notation.